1. Field of the Invention
This invention relates to vehicles, and more particularly, to vehicles that have the capability of traversing various types of terrain.
2. Description of the Related Art
Throughout the centuries, man has searched for ways to travel over uneven surfaces for performing various activities in both civilian and military situations. In situations such as surveillance, exploration, target acquisition and/or designation, data acquisition, communications relay, decoy, jamming, persecution, weapons or supply deliveries, a number of men and equipment must move back and forth on rough terrain to complete a task.
The prior art shows that four-wheel drive vehicles are the preferred vehicles used for traveling through a rough terrain. These vehicles can, given enough time, go almost anywhere the field operations require them to go, but speed is, in most instances, severely held back by mud all spring, snow all winter, and bumpy ground all year. In many thousands of miles of off-road driving, the speed of a four-wheel drive truck is limited to only three to five miles per hour on seemingly flat or gently rolling terrain because the small surface irregularities of the ground will tear up the truck and bruise the driver at speeds over five miles per hour.
It seems obvious that a better form of off road transportation is needed. The easiest solution would appear to be a vehicle that can fly just above the bumps, but once the vehicle becomes an aircraft, costs and complexity seem to make it uneconomical to use in the field.
One of the most versatile tactical aircraft is the helicopter that is well suited to both day and night operations due to its unique ability to hover. Helicopters are great to use in the field, but at a current rate of approximately one hundred twenty-five dollars per hour, they cannot compete with the four-wheel drive vehicles for much of the market.
In recent years, the prior art shows the use of ground effect vehicles for performing, various activities in both civilian and military situations where the use of four-wheel drive vehicles is not appropriate and/or feasible.
Ground effect vehicles are those vehicles which receive reduced drag due to the reduction of wing-tip vortices while traveling at low altitudes near ground, and more typically, near water.
U.S. Pat. No. 4,282,946 entitled “Multi-Terrain Vehicle” to MacGuire, discloses a multi-terrain vehicle for traveling on or above the ground or the like. The multi-terrain vehicle has a rigid body portion and a series of rigid ribs that are rotatably connected on each side of the body portion that are capable of being rotated to their fully deployed positions. A sailcloth made from a material known by the trademark Dacron is located between each of the ribs so that the ribs and the sailcloth provide a collapsible air duct. When these air ducts are extended and provided with a source of air, this air can cause the multi-terrain vehicle to float or be located above the ground or the like. The rigid ribs also have spring members or the like that permit them to be self-adjusting to automatically maintain proper ground clearance. When the ducts are deployed, the multi-terrain vehicle can be moved horizontally over the ground by controlling the amount of airflow through the various ducts. The multi-terrain vehicle also has retractable wheels that permit it to travel over suitable terrain such as a road or the like. When these retractable wheels are extended, the collapsible ducts would normally be collapsed up against the respective sides of the body portion. The collapsible ducts and the retractable wheels of the multi-terrain vehicle permit it to travel over a wide variety of types of terrain.
The Multi-Terrain vehicle of MacGuire can fly just over the bumps with comparatively little power and is a simple vehicle, but the pure ground effect machine has inherent disadvantages. The vehicle cannot be easily transported on public highways or fit through narrow canyons or gates so the base must fold up into a smaller truck-size package for practicality.
In recent years, the marine engineering arts have developed a ground effect craft that either induces ground effect, such as a hovercraft, or utilizes some benefits of ground effect in combination with hydrodynamic hull and fin arrangements, such as catamarans and hydrofoils. Other maritime ground effect aircraft are being developed, and typically include ground effect wings to provide greater stability and lift. They cannot, however, sustain flight without maintaining close distance to the ground.
Hovercrafts perform very well in small to moderate waves because the air cushion insulates the passengers from the wave shock. Unfortunately for the hovercraft, when the seas reach a certain height, the skirt looses contact with the water in the troughs of the waves, and the air cushion gushes out.
Hovercraft can operate over water, ice, mud, snow, and soft sand for limited distances; however, they have difficulty with uneven surfaces like rocks, ice packs or high waves. The hovercraft reduces the drag by pumping air under the hull so when they are stationary, they loose the cushion and wallow in the sea. Another problem with hovercraft is they do not handle well although they are very adaptable.
Another disadvantage presented by the Hovercraft is that it is designed to work mainly in water. Water surface is very different than land surface, thus a vehicle that is good in water, may not work in land.
The prior art also teaches the use of Wing in Ground effect (WIG) vehicles (flying boats); this type of vehicle intended to cruise just above wave crests so as to avoid all but very occasional water contact during flight. Wig aircraft possess one or more wings that are generally larger than the foils of hydrofoil craft. When a WIG aircraft has accelerated to a sufficient velocity through the water, the aerodynamic lift created by the wings, lifts the aircraft out of the water. WIGs fly close to the water so that the increased lift efficiency provides transportation with less drag than they would encounter at higher altitudes.
WIG aircraft are still theoretical, but they should travel fast and operate over water, land, ice, mud, snow, and soft sand. Their drag to lift ratios is very good, but they require smooth surfaces to land and take off. They also have technical difficulties in rough air commonly found over waves and other irregular terrains. Their load flexibility is similar to airplanes so they are only useful for high value cargoes at this time. The WIG designers seem preoccupied with making an existing airplane concept fly close to the ground and have not looked at land bound vehicle design for solutions.
U.S. Pat. No. 5,592,894 entitled “Spidercraft” to Johnson, discloses a craft supported by a wave rider pod consisting of very large wheels and ground effect wings connected to a suspension system to absorb the shocks from planning over rough seas or rolling over rough terrain. This craft possesses at least one hull or cabin, at least one support arm with a suspension system, and at least one flotation wheel. The suspension system with springs and shock absorbers allows the wave rider pod to move in concert with the waves or rough terrain while the cabin of the craft remains relatively stable.
A disadvantage presented by the Spidercraft is that the size of the vehicle does not allow the vehicle to fit through narrow canyons or gates.
In summary, the vehicles discussed above do not travel fast, are designated to work in water, and are too big to fit through narrow canyons or gates or require smooth surfaces to land and take off.
It appears from the prior art that no invention has a satisfactory solution for traveling over land, ice, mud, snow and soft sand without slowing down for rough conditions.